Light emitting devices such as light emitting diodes and laser diodes which use a Group III-V or Group II-VI semiconductor material may render various colors such as red, green, blue, and ultraviolet by virtue of development of thin film growth technologies and device materials. It may also be possible to produce white light at high efficiency using fluorescent materials or through color mixing. Furthermore, the light emitting devices have advantages such as low power consumption, semi-permanent lifespan, fast response time, safety, and environmental friendliness as compared to conventional light sources, such as fluorescent lamps and incandescent lamps.
Therefore, these light emitting devices are increasingly applied to transmission modules of optical communication units, light emitting diode backlights as a replacement for cold cathode fluorescence lamps (CCFLs) constituting backlights of liquid crystal display (LCD) devices, lighting apparatuses using white light emitting diodes as a replacement for fluorescent lamps or incandescent lamps, headlights for vehicles and traffic lights.
FIG. 1 is a cross-sectional view briefly illustrating a conventional light emitting device. The conventional light emitting device includes a substrate 10, a light emitting structure, which includes an n-GaN layer 20, an active layer 30, and a p-GaN layer 40, an n-electrode 60 disposed on the n-GaN layer 20, and a p-electrode disposed on the p-GaN layer 40.
The p-GaN layer 40 includes an electron blocking layer (EBL) 50 to be adjacent to the active layer 30. Since electrons have far greater mobility than holes, overflow of electrons out of the active layer 30 into the p-GaN layer 40 may be prevented by inserting the EBL 50 having a high energy barrier thereinto.
However, while internal quantum efficiency is improved by the EBL 50 via blocking overflow of electrons, the EBL 50 also blocks inflow of holes as a barrier.